This section provides background information related to the present disclosure which is not necessarily prior art.
A cyclopropene-based compound, 1-methylcyclopropene (1-MCP), is a highly effective inhibitor for ethylene receptor, which functions by acting irreversibly on the ethylene receptor in a manner of binding preferentially to the ethylene receptor, blocking the binding of an endogenous ethylene and an exogenous ethylene to the ethylene receptor, thereby inhibiting a series of physiological and biochemical reactions including after-ripening or aging of horticultural plants such as flowers, vegetables and fruits, so as to attain an objective of preserving foods such as flowers, vegetables and fruits in storage and transportation.
1-MCP is a highly reactive olefin, having a boiling point of 10° C., present in gas form at normal temperature. A fumigation method is carried out in on-site operation in a manner that an amount of 1-MCP gas is predetermined and then placed into a closed space to function, which is therefore very inconvenient in use. In order to enhance the convenience for using 1-MCP and the stability during the storage thereof, U.S. Pat. No. 6,017,849 proposed a method for encapsulating 1-MCP with a carrier, for example, a carrier of α-cyclodextrin could be used for stabilizing the reactivity and instability of 1-MCP gas.
The cyclodextrin is a cyclic glucose oligosaccharide, having a special cylinder-shaped structure. The glucose monomer has a polar hydroxyl group located on the surface of the cylinder structure, rendering the external of the cyclodextrin hydrophilic. On the contrary, the cylindrical inner hole is non-polar and lipophilic, so the inner hole of the cyclodextrin can form a complex with the other molecules, which can be released under a certain condition. Recently, the cyclodextrin has been widely used in fields such as foods, pharmacy, chemical, agriculture and environmental engineering. Currently, there are crystals having 6, 7, 8 or 9 glucose units linked annularly via α-1,4 linkages, referred as α-Cyclodextrin, β-Cyclodextrin, γ-Cyclodextrin or δ-Cyclodextrin, respectively.
The technique of solid 1-MCP is mainly to use the cyclodextrin to immobilize 1-MCP gas, which can be released upon mixing the powder with water or a buffer solution, thereby the application range of 1-MCP can be extended. When use on-site, it is only necessary to add water or a buffer solution, thus the trouble of gas transportation can be avoided and the convenience for on-site staffs operation can be enhanced. Therefore, an easy and safe method for storing, transporting, using or delivering the gas to a plant can be provided. The technique for immobilizing 1-MCP gas with cyclodextrin has been successfully commercialized and marketed and approved in 1999 by EPA (Environmental Protection Agency) in US.
Although the solid powder product is much more convenient in use than the gaseous product, it still has a number of limitation and disadvantages in the application, and is disadvantageous for use by general users. Therefore, the development of various dosages of 1-MCP becomes a focus for the subsequent commercial applications of 1-MCP. PCT Patent Application Publication No. WO 02/24171A1 discloses an effervescent tablet dosage formulation which alleviates the disadvantages of mixing associated with the powder form. This product of tablet dosage is easily metered, and has a controlled release mechanism which cannot be achieved by the powder type formulation. As compared with the powder type product, these tablet dosages are easy to use for non-specialized customers, florists and wholesalers. However, these effervescent tablet dosage products of 1-MCP still have limitation in use, since it is usually necessary to circulate air to ensure a uniform distribution of 1-MCP gas. If 1-MCP has a non-uniform concentration in atmospheric environment, it tends to cause a non-uniform ripening response in plants. However, the requirement of using circulating air in a wild field is not easy to meet, which may further lead to an impairment of the commercial benefits of the product.
TW Patent No. I 265005 discloses a non-woven fabric-based laminate which is prepared by interposing a composition, including 1-MCP and a thermoplastic polymer, between non-woven fabrics or other layered materials, and immobilizing 1-MCP onto the layered materials and bonding the layered materials through the adhesion effect of the thermoplastic polymer. However, during the preparation, it is necessary to mix the 1-MCP powders with the thermoplastic polymer powders before spraying the powders directly onto the non-woven fabric, thus a problem of non-uniform distribution of 1-MCP may occur easily, which may further result in a non-uniform releasing concentration of the product 1-MCP.